The invention relates to a process for preparing a thread for the re-piecing of an open-end spinning apparatus, in which the thread end is cut to the length of a piecable thread end, and to an apparatus for carrying out the process.
It is known to draw off from a bobbin the thread end required for the re-piecing of an open-end spinning apparatus, shorten it to a predetermined length (cut it to length), and then guide the thread end thus prepared back to the fiber-collection surface of the open-end spinning apparatus, where it is joined to the fibers fed onto the collecting surface (German Auslegeschrift No. 1,710,021 which is U.S. Pat. No. 3,455,095). The spinner usually cuts the thread end to length by severing the thread by means of a fingernail or, where stronger threads are concerned, over an edge, so that a frayed, but definite thread end is obtained. The thread end produced simply as a result of cutting usually does not provide sufficient piecing conditions, so that, particularly at high rotor speeds, the success rate for joining the thread is inadequate.
It is also known to shorten the thread purely pneumatically to the length desired for joining (German Offenlegungsschrift No. 2,203,198). In this case, the free thread end is untwisted by a circulating air flow and detached from the remaining thread by being pulled pneumatically, so that a thread end with a fiber tuft is obtained.
Apart from the fact that this does not produce an exact point of separation and consequently a specific length of the thread end, it has been shown, when threads are joined at high rotor speeds, that the success rate of the joining operation is, as before, unsatisfactory.